| 1. |
- Borrajo-Pelaez, Rafael, et al.
(author)
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Recent Developments of Crystallographic Analysis Methods in the Scanning Electron Microscope for Applications in Metallurgy
- 2018
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In: Critical reviews in solid state and materials sciences. - : TAYLOR & FRANCIS INC. - 1040-8436 .- 1547-6561. ; 43:6, s. 455-474
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Research review (peer-reviewed)abstract
- The field of metallurgy has greatly benefited from the development of electron microscopy over the last two decades. Scanning electron microscopy (SEM) has become a powerful tool for the investigation of nano- and microstructures. This article reviews the complete set of tools for crystallographic analysis in the SEM, i.e., electron backscatter diffraction (EBSD), transmission Kikuchi diffraction (TKD), and electron channeling contrast imaging (ECCI). We describe recent relevant developments in electron microscopy, and discuss the state-of-the-art of the techniques and their use for analyses in metallurgy. EBSD orientation measurements provide better angular resolution than spot diffraction in TEM but slightly lower than Kikuchi diffraction in TEM, however, its statistical significance is superior to TEM techniques. Although spatial resolution is slightly lower than in TEM/STEM techniques, EBSD is often a preferred tool for quantitative phase characterization in bulk metals. Moreover, EBSD enables the measurement of lattice strain/rotation at the sub-micron scale, and dislocation density. TKD enables the transmitted electron diffraction analysis of thin-foil specimens. The small interaction volume between the sample and the electron beam enhances considerably the spatial resolution as compared to EBSD, allowing the characterization of ultra-fine-grained metals in the SEM. ECCI is a useful technique to image near-surface lattice defects without the necessity to expose two free surfaces as in TEM. Its relevant contributions to metallography include deformation characterization of metals, including defect visualization, and dislocation density measurements. EBSD and ECCI are mature techniques, still undergoing a continuous expansion in research and industry. Upcoming technical developments in electron sources and optics, as well as detector instrumentation and software, will likely push the border of performance in terms of spatial resolution and acquisition speed. The potential of TKD, combined with EDS, to provide crystallographic, chemical, and morphologic characterizations of nano-structured metals will surely be a valuable asset in metallurgy.
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| 2. |
- Xiong, Wei, et al.
(author)
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Phase Equilibria and Thermodynamic Properties in the Fe-Cr System
- 2010
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In: Critical reviews in solid state and materials sciences. - : Informa UK Limited. - 1040-8436 .- 1547-6561. ; 35:2, s. 125-152
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Research review (peer-reviewed)abstract
- Phase equilibria and thermodynamic properties in the Fe-Cr system have been reviewed comprehensively based on experimental information and available computer simulations in different scales. The evaluated phase equilibria show significant differences from the currently accepted thermodynamic description by CALPHAD (calculation of phase diagram) approach. The thermodynamic properties of the Fe-Cr system, such as heat capacity, enthalpy, and activity, have been evaluated in reported experiments. The experiments on phase separation in the Fe-Cr system have also been critically reviewed with a focus on spinodal decomposition. The reported data are concentrated in the temperature range from 673 to 823 K. In addition, there is a transition region between spinodal decomposition and nucleation regimes within the composition limit from 24 to 36.3 at.% Cr and the temperature range between 700 and 830 K. In view of the importance of magnetism in the Fe-Cr system, some inadequacies of the currently used thermodynamic description are pointed out in addition to some problems with the current magnetic model. Remaining issues on the thermodynamics of the Fe-Cr system have been elaborated for future refinement of the thermodynamic description of the Fe-Cr system. According to the present review, the melting temperature of Cr is recommended to be about 2136 K, which is 44 K lower than the value adopted in the research community on thermodynamics, such as the Scientific Group Thermodata Europe.
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| 3. |
- Zhang, Shi-Li, et al.
(author)
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Metal silicides in CMOS technology : Past, present, and future trends
- 2003
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In: Critical reviews in solid state and materials sciences. - : Informa UK Limited. - 1040-8436 .- 1547-6561. ; 28:1, s. 1-129
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Research review (peer-reviewed)abstract
- Metal silicides have played an indispensable role in the rapid developments of microelectronics since PtSi was first used to improve the rectifying characteristics of diodes in early 1960s. This work first provides a brief historical overview of the many different silicides, and, correspondingly. the different processing methodologies used in the past. With regard to the present use of silicides in CMOS technologies, a convergence becomes clear with the self-aligned technology using only a limited number of silicides, namely, TiSi2, CoSi2, and NiSi. A section on fundamental aspects is included to cover thermodynamics and kinetics, which are essential for understanding the silicide formation processes. The advantages and disadvantages of TiSi2, CoSi2, and NiSi are analyzed with the development trend of CMOS technologies as a measure. Specifically, the reactive diffusion and phase formation of these silicides in the three terminals of a metal-oxide-semiconductor device, that is, gate, source, and drain, are scrutinized. The review ends with an extended discussion about future trends of metal silicides in micro/nanoelectronics, with reference to the potential material aspects and device structures outlined in the International Technology Roadmap for Semiconductors.
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| 4. |
- Zhou, Tao, et al.
(author)
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On the role of transmission electron microscopy for precipitation analysis in metallic materials
- 2021
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In: Critical reviews in solid state and materials sciences. - : Informa UK Limited. - 1040-8436 .- 1547-6561. ; , s. 1-27
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Journal article (peer-reviewed)abstract
- Precipitation hardening is one of the most important strengthening mechanisms in metallic materials, and thus, controlling precipitation is often critical in optimizing mechanical performance. Also other performance requirements such as functional and degradation properties are critically depending on precipitation. Control of precipitation in metallic materials is, thus, vital, and the approach presently in the limelight for this purpose is an integrated approach of theory, computations and experimental characterization. An empirical understanding is essential to build physical models upon and, furthermore, quantitative experimental data is needed to build databases and to calibrate the models. The most versatile tool for precipitation characterization is the transmission electron microscope (TEM). The TEM has sufficient resolving power to image even the finest precipitates, and with TEM-based microanalysis, overall quantitative data such as particle size distribution, volume fraction and number density of particles can be gathered. Moreover, details of precipitate structure, morphology and chemistry, can be revealed. TEM-based postmortem and in situ analysis of precipitation has made significant progress over the last decade, largely stimulated by the widespread application of aberration corrected microscopes and accompanying novel analytics. The purpose of this report is to review these recent developments in precipitation analysis methodology, including sample preparation. Application examples are provided for precipitation analysis in metals, and future prospects are discussed.
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